As mentioned above, technically one needs to seek approval from the trademark owner before putting it out there. However, if the trademark owner wanted to get upset about it, they could request a take-down, which I'm sure thingiverse would immediately oblige to. Here at https://3Dagogo.com we have the same policy...

At that point, if they wanted to sue, they would have to show that damages occurred. If you were profiting from the design, there are some damages. This is one reason it is more important to us than it is to Thingiverse. At 3Dagogo, you can profit from the design, therefore there can be immediate damages. They could also go for damages if they felt you defaced their company in some fashion.

The reality is that these companies mostly don't care about this unless it becomes a bit bigger.

3DP is definitely moving that direction and this type of thing will become a serious issue, but for now it's all still in good fun! Enjoy the moment!

Drew
Cofounder, CEO
https://3Dagogo.com